METHOD FOR CONTROLLING A DRIVETRAIN IN A HYBRID VEHICLE AND HYBRID VEHICLE

Description

[0001] The invention relates to a method for controlling a drive train in a hybrid vehicle and a hybrid vehicle.

[0002] In hybrid vehicles, propulsion can be purely electric, mixed electric / non-electric, or purely non-electric. For this purpose, a hybrid vehicle can have a first drive, such as an electric motor, and a further drive, such as an internal combustion engine. During purely electric propulsion, for example, the electric motor is switched on, while the internal combustion engine can be switched off. However, the internal combustion engine can be started, for example, to relieve the load on the electric motor in mixed propulsion or to provide full drive power. It is also known that the internal combustion engine is started, for example, to supply a battery of the electric drive with power via a generator.

[0003] With the continuous tightening of emissions legislation, it may be necessary to operate an internal combustion engine, e.g. after a cold start, with reduced power, for example at idle, in order to heat up the exhaust gas aftertreatment components to a permissible operating state.

[0004] In order to reduce unnecessary emissions during the operation of an internal combustion engine or to prevent them from occurring in the first place, various methods for operating hybrid vehicles are known from the state of the art.

[0005] DE 102019 127 720 A1 proposes achieving correspondingly low pollutant emissions during cold operation of an internal combustion engine by driving the hybrid-electric vehicle solely by the electric drive motor during a first operating phase. In parallel, the internal combustion engine is operated—preferably at idle—to temper the exhaust gas aftertreatment system to a predefined temperature. In a second operating phase, in which the exhaust gas aftertreatment system is heated accordingly, the hybrid-electric vehicle is then driven by the internal combustion engine. It is also described that the start of the first operating phase is predictively determined depending on the charge state of the hybrid-electric vehicle's battery.

[0006] WO 2020 / 232104 A1 relates generally to hybrid vehicles, in particular to improving the fuel consumption of hybrid vehicles.

[0007] DE 10 2016 106 466 A1 relates to systems and methods for controlling the operation of an engine in a vehicle with an internal combustion engine.

[0008] US 2013 / 0 166 122 A1 relates to a generic method for controlling a drive train in a hybrid vehicle.

[0009] Furthermore, it is known that electric motors can heat up as a result of a corresponding load, which can lead to undesirable performance losses or even damage to the electric motor.

[0010] The technical problem is to create a method for controlling a drive train in a hybrid vehicle and a corresponding hybrid vehicle that further reduce emissions during operation of a hybrid vehicle. Preferably, the created method and the corresponding hybrid vehicle can further improve aspects of the provision of drive power and / or the cooling of the drive train.

[0011] The solution to the technical problem is achieved by the subject matter having the features of the independent claims. Further advantageous embodiments of the invention are set forth in the subclaims.

[0012] A method is therefore proposed for controlling a drive train in a hybrid vehicle, wherein the drive train has at least one first drive and at least one further drive, the method comprising the following steps: Monitoring a power provided for operating the first drive, determining at least one start parameter depending on the power provided, evaluating whether the at least one start parameter fulfills a start criterion, starting the further drive if the at least one start parameter fulfills the start criterion.

[0013] According to the invention, the at least one start parameter is determined as an amount of energy provided for operating the first drive, wherein the start criterion is met if the amount of energy provided is greater than or equal to a threshold amount of energy. This ensures that the amount of energy provided for operating the first drive is limited to the threshold amount of energy before the additional drive is started. This ensures, for example, that a residual amount of energy is available in the battery as a reserve for emergencies.

[0014] Furthermore, according to the invention, the amount of energy provided is determined as a time integral over the power provided from a first point in time to an actual point in time. The time integral can also be referred to as a power integral. The time integral can be carried out, for example, by numerically integrating the values ​​of the power provided from a first point in time to an actual point in time. For this purpose, the method can access, for example, a time profile of the power provided via the previously explained memory unit. The first point in time can correspond, for example, to the start of operation of the first drive, i.e., for example, the point in time at which a journey with the hybrid vehicle began.

[0015] Preferably, the first drive is an electric drive. The first drive can, for example, comprise an electric motor or be designed as such. In particular, an asynchronous motor, a permanent magnet-excited synchronous motor, or an externally or current-excited synchronous motor are considered. The first drive can be powered, for example, by a battery. The battery can be part of the first drive and / or the drive train.

[0016] Preferably, the additional drive is a non-electric drive. The additional drive can, for example, comprise an internal combustion engine or be designed as such. The internal combustion engine can be powered by diesel or gasoline, for example. Furthermore, the additional drive can have exhaust gas aftertreatment to reduce emissions.

[0017] It is of course conceivable that the drive train in a hybrid vehicle has additional machine elements for converting motion variables or for power and energy conversion, such as a gearbox, a clutch, or a generator.

[0018] Preferably, the hybrid vehicle is driven exclusively by means of the first drive before starting the further drive, ie the drive power required to move the hybrid vehicle is provided solely by the first drive.

[0019] The power provided can correspond to the power requested by a user of the hybrid vehicle or correlate with the requested power. Furthermore, the user can adjust the requested power, for example, by adjusting the pedal travel. The power provided can therefore have different values ​​at different times.

[0020] Preferably, the power provided to operate the first drive is determined using parameters. For example, the voltage and current applied to the first drive can be recorded as parameters. From this, a current value of the provided electrical power can then be determined, i.e., a power value for an actual point in time. The actual point in time can, for example, designate a point in time at which the parameters were recorded. Furthermore, the actual point in time can include a timestamp so that parameters or determined values ​​can be assigned to the actual point in time.

[0021] Monitoring means that the power provided, in particular the current power, for operating the first drive is determined. The monitoring can, for example, comprise, in particular, sensor-based detection of parameters of the first drive. Of course, further or different parameters of the hybrid vehicle can also be detected to determine the power provided. Corresponding methods for detecting parameters and for determining the power of a drive are known to those skilled in the art. Monitoring advantageously results in the power provided for operating the first drive being quantified and thus being able to be used for further processing within the method.

[0022] The start parameter or a value of the start parameter is determined depending on the determined power. In other words, the start parameter is a function of the power provided to operate the first drive. In the simplest embodiment, the start parameter is determined as a value of the provided power. For this purpose, the determined value of the provided power can be assigned to the start parameter, for example, for an actual point in time. However, the start parameter can also be determined depending on the provided power in a different way, as explained below.

[0023] The start criterion must be met to enable the start of the additional drive. The start parameter or the specific value of the start parameter is used to evaluate the start criterion. In other words, the start criterion can, for example, be a condition that must be met by the start parameter or a specific value of the start parameter before the additional drive is started. This ensures that the start of the additional drive is dependent on the power provided by the first drive. This can, for example, ensure that the additional drive is only started when this is deemed necessary depending on the power provided. This can be the case, for example, because the load on the first drive is to be relieved for cooling purposes and at least a portion of the drive power is to be provided by the additional drive.

[0024] The start criterion can, for example, require that a certain value of the start parameter be greater than or equal to a threshold. If the threshold is exceeded, for example, by the provided power, the start criterion is met, and starting of the other drive is enabled.

[0025] The threshold value can be predetermined and, for example, correspond to a predetermined continuous power of the first drive. For electric motors, for example, it is common for a continuous power to be known in advance from tests. The continuous power corresponds, for example, to a value of the power of the electric drive that can be provided continuously. If the continuous power is exceeded, especially over a longer period of time, this can lead to above-average heat generation in the electric drive.

[0026] If the start criterion is met, the additional drive is started. Starting the additional drive can of course involve generating an electrical signal and the corresponding output to the additional drive. The signal can in particular be generated by a controller of the hybrid vehicle or a device for controlling the drive train. Starting the additional drive can take place, for example, using a starter. It is also conceivable for starting to take place, for example, using the first drive, e.g. via a corresponding mechanical coupling. For example, the first drive can start the additional drive by closing a corresponding clutch. In this way, for example, a starter for starting the additional drive in the hybrid vehicle can be omitted, which in particular saves weight and costs.

[0027] Preferably, starting the additional drive involves providing at least a portion of the drive power, e.g., by transferring the power to a transmission. This allows the first drive to operate at lower power and reduce the load accordingly.

[0028] Preferably, one or more of the explained steps of the method according to the invention are carried out continuously, in particular iteratively. In particular, one iteration of the method is carried out for each actual point in time. Of course, not all steps of the method have to be carried out completely in one iteration of the method, e.g. if the start criterion is not met, the iteration is ended without the additional drive being started. If the start criterion is met, the starting of the additional drive is released and initiated in the current iteration. By iteratively carrying out the method, for example, a temporal profile of the power provided or the power values ​​can be created, in particular for the respective actual points in time.

[0029] Furthermore, the determined results or values ​​of the method can be stored, e.g., in a corresponding storage unit that may be part of the hybrid vehicle. Of course, the method can access results or values ​​from previous iterations.

[0030] The actual point in time can, as previously explained, include a timestamp that marks the beginning of an iteration. Thus, a value of the provided performance can be temporally marked for each actual point in time. Of course, further steps or results and / or values ​​of the process can also be temporally marked by the actual point in time. The time period between two actual points in time can be referred to as the runtime of the process.

[0031] The method according to the invention delays the start of the additional drive for as long as possible, thereby avoiding emissions accordingly. For this purpose, a time at which the additional drive starts is determined by evaluating the start criterion. By taking into account the power provided by the first drive, it can be ensured that the power provided is sufficient, e.g. to move the hybrid vehicle, or that the additional drive is started if the first drive would be overloaded or even damaged, e.g. as a result of power-related heat development. The method according to the invention therefore avoids emissions that would result from the unnecessary operation of the additional drive. On the other hand, the method according to the invention ensures that the additional drive is started as soon as this is deemed necessary, e.g. for cooling the first drive.This prevents unwanted overloading of the first drive.

[0032] In a further embodiment, the start criterion is determined depending on a peak power value of the first drive. The peak power corresponds to a maximum value of the available power during operation of the first drive. This means that the maximum value is the maximum power that can technically be provided for operating the first drive. For example, it is common for a peak power for an electric drive to be known or predetermined from tests. For an electric drive, the peak power value corresponds, for example, to approximately twice the value of the continuous power that can be provided.

[0033] By including peak power, the start of the additional drive depends not only on the power provided by the first drive, but also on the technically available power—namely, the peak power—of the first drive. The start criterion can be assigned, for example, the value of the peak power as a threshold. The additional drive is then started, for example, when the peak power is reached.

[0034] In a further embodiment, the start criterion is determined as a function of a time period required to preheat the additional drive. The time period required to preheat the additional drive can also be referred to as the preheating period. The preheating period corresponds in particular to the time period required to preheat an exhaust gas aftertreatment system of the additional drive to a predetermined operating temperature. The value of the preheating period can be known in advance, for example, from tests and thus be predetermined.

[0035] Preheating is preferably carried out by means of a heating element. The heating element can be part of the additional drive. In particular, starting the additional drive can mean that the heating element is switched on to preheat the additional drive and thus, for example, preheats the exhaust gas aftertreatment system. The heating element can be designed, for example, as a heating resistor and supplied with energy by a battery of the hybrid vehicle. Alternatively or cumulatively, the exhaust gas aftertreatment system can also be heated after starting the additional drive by waste heat during operation of the additional drive, such as by exhaust gases from an internal combustion engine.

[0036] It should be noted that preheating the additional drive can also be achieved using waste heat from the primary drive. This allows the primary drive to be cooled while the additional drive is preheated. This increases the energy efficiency of the process and the hybrid vehicle.

[0037] In a further embodiment, the value of the time required to preheat the additional drive is determined as a function of an actual temperature of the additional drive. An actual temperature of the additional drive can be determined by a sensor. The actual temperature refers in particular to an actual temperature of the exhaust gas aftertreatment. The time required to preheat the additional drive can, for example, be shorter if the actual temperature is higher than a predetermined reference temperature or longer if the actual temperature is lower than a predetermined reference temperature. The reference temperature can, for example, correspond to the ambient temperature. The extent by which the time period changes as a function of the actual temperature can be predetermined. This makes it possible to take into account how long the additional drive actually needs to be preheated, for example to reach a desired operating temperature, when starting the additional drive.In particular, unnecessary emissions caused by preheating the further drive for too short or too long can be avoided.

[0038] Furthermore, the amount of energy provided can correlate with, for example, the heat input into the first drive. By determining the amount of energy provided, the heat input already absorbed can also be taken into account. The additional drive can then be started when the load on the first drive needs to be reduced accordingly, for example, for cooling purposes.

[0039] The respective energy quantities can be determined, for example, using the voltage values ​​of a battery. However, other methods of determining the energy quantities are also conceivable, as explained below.

[0040] It is also conceivable that the value of the provided energy quantity is reduced by a predetermined value. For example, the value of the provided energy quantity can be reduced by the predetermined value if a value of the provided power determined at an intermediate point in time is smaller than a value of the provided power at a previous point in time. In this way, for example, cooling effects resulting from a reduced power requirement for the first drive can be taken into account. The value for reducing the power integral can, for example, be predetermined from tests and correlate with a corresponding cooling capacity of the first drive.

[0041] In a further embodiment, the threshold energy quantity is determined as the value of a subset of a maximum energy quantity, wherein the maximum energy quantity corresponds to the amount of energy required to provide peak power over a maximum period of time. The maximum period of time therefore corresponds to a period of time for which the peak power is maximally available to operate the first drive before the first drive would be overloaded, e.g. due to heat generation. The maximum period of time can be known or predetermined, e.g. from tests. Using the maximum period of time and the value of the peak power, the maximum amount of energy that would be used to operate the first drive at peak power can thus be determined. The maximum amount of energy can be determined, e.g., by temporal integration.

[0042] The subset of the maximum energy quantity can be determined, for example, using a scaling factor. The scaling factor is preferably a value between zero and one, so that the subset is less than or equal to the maximum energy quantity. This ensures that the threshold energy quantity corresponds at most to the maximum energy quantity.

[0043] The subset of the maximum energy quantity can also be determined, for example, depending on the time required to preheat the remaining drive. For this purpose, the subset can be determined, for example, by integrating the peak power over a period of time corresponding to the difference between the maximum time and the preheating time.

[0044] In a further embodiment, the at least one start parameter is determined only when the provided power is greater than or equal to a predetermined continuous power value of the first drive. This corresponds to a pre-criterion that precedes the actual start criterion. This advantageously ensures that the start criterion is only evaluated when the provided power equals or exceeds the continuous power value.

[0045] In a preferred embodiment, the previously explained first point in time is determined when the provided power is greater than or equal to a threshold value. The threshold value can, in particular, correspond to the continuous power value of the first drive.

[0046] In a further embodiment, the additional drive is not started until the power provided for operating the first drive has been reduced by a value that corresponds to the power required to start the additional drive. For example, it is conceivable that the saved power of the first drive, which becomes available due to the reduction, is made available to a starter of the additional drive for starting the additional drive. This ensures that the value by which the provided power was reduced is available to start the additional drive. After the additional drive has been started, the provided power of the first drive can be increased or boosted back to the original value.

[0047] Preferably, the reduction in the provided power occurs as a continuous transition function. This means that the power is reduced in smooth steps until the desired reduction value is reached. This ensures that the drive power is not reduced abruptly, which increases driving comfort for the user. Of course, the provided power can also be increased again as a continuous transition function once the further drive has been started.

[0048] Further proposed is a hybrid vehicle having a drive train, wherein the drive train has at least one first drive and at least one further drive, wherein the hybrid vehicle further comprises a device for controlling the drive train, wherein the device is designed to carry out a method according to an embodiment described in this disclosure.

[0049] The device for controlling the drive train can be designed as a microcontroller or include one. The device can be connected via signaling to the first drive and the additional drive. Of course, the device can also be connected via signaling to other machine elements of the hybrid vehicle.

[0050] In particular, the device can receive and process the signals necessary for executing the method according to the invention, and generate and output signals, in particular at least one signal for starting the additional drive. The device can further comprise or form the previously explained storage unit or be connected to it via signaling technology.

[0051] Using the proposed hybrid vehicle, a method can be implemented that can achieve one or all of the technical effects mentioned in this disclosure. The advantages resulting from these technical effects also apply accordingly to the hybrid vehicle according to the invention.

[0052] Further proposed is a computer program product comprising a computer program, wherein the computer program comprises software means for executing one, several, or all steps of the method according to the invention according to one of the embodiments described in this disclosure, in particular for executing monitoring, determining, evaluating, and starting. The computer program can be executed by or in a computer or by the described device for controlling the drive train.

[0053] This means that the method according to the invention is, for example, a computer-implemented method. For example, all steps or only some of the steps (ie, fewer than the total number of steps) of the method according to the invention can be performed by a computer or the device. One embodiment of the computer-implemented method is the use of the computer or the device to carry out the method according to the invention.

[0054] The computer program product advantageously enables the implementation of a method according to the invention according to one of the embodiments described in this disclosure, for which technical advantages have been described above.

[0055] The invention is explained in more detail using exemplary embodiments. The figures show: Fig. 1 is a schematic representation of a first embodiment of the invention of a hybrid vehicle, Fig. 2 is a flow chart of a first embodiment of the invention of a method for controlling a drive train in a hybrid vehicle, Fig. 3 is a first pair of diagrams for determining a start parameter in a first embodiment of the invention of the method, Fig. 4 is a schematic representation of a further embodiment of the invention of a hybrid vehicle, Fig. 5 is a flow chart of a further embodiment of the invention of a method for controlling a drive train in a hybrid vehicle and Fig. 6 is a further pair of diagrams for determining a start parameter in a further embodiment of the method according to the invention.

[0056] In the following, the same reference symbols designate elements with the same or similar technical features.

[0057] Fig. 1 shows a schematic representation of an embodiment of a hybrid vehicle 1 according to the invention. The hybrid vehicle 1 comprises a drive train 2. In the illustrated embodiment, the drive train 2 has a first drive 3, which is designed as an electric motor. A battery 15 supplies the first drive 3 and other electrical or electronic components with electrical energy.

[0058] Furthermore, the drive train 2 has a further drive 4, which includes an internal combustion engine 4-1 and an exhaust gas aftertreatment system 4-2. An associated tank for supplying fuel to the internal combustion engine 4-1 is not shown.

[0059] The drive train 2 further comprises mechanical elements such as a transmission 13, which transmits the power from the first drive 3 and / or from the additional drive 4 to an axle or the corresponding wheels of the hybrid vehicle 1. Further mechanical elements include a clutch 14 between the additional drive 4 and the transmission 13, so that the power generated by the additional drive 4 can be used directly for propulsion, for example. After starting the additional drive 4, the first drive 3 can of course also be used as a generator, and the energy provided by the additional drive 4 can be converted into electrical energy for charging the battery 15.

[0060] Furthermore, the hybrid vehicle 1 comprises a device 30 for controlling the drive train 2. The device 30 has a microcontroller and, in the embodiment shown, is designed to Fig. 2 shown method for controlling the drive train 2. Signals for executing the method can be transmitted to the device 30 via corresponding lines (in Fig. 1 shown as simple lines). A line that can conduct a signal S for starting the internal combustion engine 4-1 from the device 30 to the further drive 4 is also shown.

[0061] Fig. 2 shows a flowchart of an embodiment of a method according to the invention for controlling a drive train 2 in a hybrid vehicle 1. The method comprises a plurality of steps S1, S2, S3 and S4, which are carried out iteratively. An iteration of the method begins with a first step S1. Each step S1, S2, S3, S4 of the method refers, within a respective iteration of the method, to a point in time which is referred to as the actual time T2. In other words: the actual time T2 corresponds to a timestamp at the beginning of the runtime of an iteration of the method. Once an iteration of the method has ended, a new iteration begins with a new actual time T2. The method begins, for example, at the beginning of a journey. The point in time at which a journey begins can be referred to as T0 (cf. Fig. 3 ).

[0062] In a first step S1, the power P provided for operating the first drive 2 is monitored. For this purpose, the voltage U and current I applied to the first drive 2 are recorded for the actual time T2, e.g., using appropriate sensors. The values ​​of the voltage U and current I are input values ​​to the method, which are processed in a numerical operation 17 to obtain a value of the provided power P for the actual time T2.

[0063] In a further step S2, a check is carried out to determine whether the determined value of the provided power P is greater than or equal to a predetermined value PD of a continuous power of the first drive 2. This check is also referred to as pre-criterion 19. If pre-criterion 19 is not met N, i.e. P < PD , the iteration for the actual time T2 is ended and a new iteration for a subsequent actual time T2 is started (represented by the arrow leading to step S1). This can be repeated until pre-criterion 19 is met. If pre-criterion 19 is met Y, the actual time T2 for which pre-criterion 19 was met is determined as the first time T1. The first time T1 serves as a reference for determining an energy quantity E.

[0064] In the next step S2, a numerical integration 18 follows, whereby the energy quantity E is determined as a time integral over the provided power P from the first time T1 to the actual time T2. The integral determined in this way can also be referred to as the power integral. The value of the power integral corresponds to the energy quantity used to provide a power above the value PD of the continuous power over the time period T1, T2. This energy quantity E can, for example, correlate with a heat input into the first drive 3, whereby the heat input should, for example, not exceed a corresponding limit value.

[0065] It should be noted that the resulting value of the integral in the first iteration after fulfilling the pre-criterion 19 is, of course, machine-accurately zero, since the first time T1 corresponds to the actual time T2 of this iteration. In subsequent iterations of the method, the value of the power integral continues to increase if the pre-criterion 19 is also fulfilled by the subsequent values ​​of the provided power P. The method can retrieve the corresponding values ​​of the power P from the previous iterations from a storage unit (not shown) for the purpose of further numerical integration 18.

[0066] The aim of the further step S2 is also to determine a start parameter 10. In this case, following the numerical integration 18, the value of the determined energy quantity E is assigned to the start parameter 10 in a numerical operation 17.

[0067] In a further step S3, the start criterion 20 is evaluated using the start parameter 10. To fulfill the start criterion 20, the current value of the start parameter 10 must be greater than or equal to a threshold energy quantity Es. The threshold energy quantity ES can, for example, be determined such that the previously mentioned limit value for a corresponding heat input into the first drive 3 is not exceeded.

[0068] In Fig. 2 the threshold energy quantity ES is determined in the further step S3 as follows. A predetermined value P MAX of the peak power of the first drive 3 and a value of an associated maximum time period T MAX as well as a scaling factor X are input values ​​into the method. The value P MAX of the peak power corresponds to the maximum power value that can theoretically be achieved by means of the first drive 3. The maximum time period T MAX corresponds to the time period over which the peak power P MAX can theoretically be made available without the previously explained heat input occurring. The scaling factor X can, for example, correspond to a predetermined safety factor by which the maximum time period T is scaled.

[0069] Using numerical integration 18, a subset E MAX of a maximum energy quantity E MAX can be determined from these input values, where the maximum energy quantity E MAX corresponds to the amount of energy required to provide the peak power P MAX over the predetermined maximum time period T MAX . The subset Ex corresponds to the maximum energy quantity E MAX scaled by the scaling factor X.

[0070] In a further numerical operation 17, the value of the subset Ex is assigned to the value of the threshold energy quantity ES. This value of the threshold energy quantity ES now forms the limit value for the current value of the start parameter 10 in the respective iteration of the procedure (see Fig. 3 ).

[0071] If the start criterion 20 is not met by the current value of the start parameter 10 N, i.e., 10 < ES , the iteration is terminated at this point and a new iteration is started (represented by the arrow leading to step S1). However, if the value of the start parameter 10 is greater than or equal to the threshold energy quantity ES , the start criterion 20 is met Y and starting of the additional drive 4 is enabled.

[0072] In a further step S4, a signal S for starting the further drive 4 is then generated by the device 30 and output to it (cf. Fig. 1 ). By starting the additional drive 4, the load on the first drive 3 can then be reduced accordingly, e.g. by providing at least a portion of the power required to move the hybrid vehicle 1 by the additional drive 4.

[0073] The method thus advantageously results in the additional drive 4 only being started when this appears necessary to relieve the load on the first drive 3. This allows unnecessary emissions from the additional drive 4 to be avoided.

[0074] Fig. 3 shows a first pair of diagrams for determining a start parameter 10 according to the first embodiment of the method according to the invention (cf. Fig. 2 ).

[0075] The upper diagram shows an idealized curve of the provided power P from a time T0, the start of a trip, to an actual time T2. Furthermore, a theoretical time T3 is shown, which corresponds to the end time of the maximum duration T MAX. The maximum duration T MAX can, for example, be predetermined and was explained previously.

[0076] At the start of the journey, according to the upper diagram, a constant value is provided as power P for operating the first drive 3, which corresponds to a value PD of the continuous power of the first drive 3. Waste heat generated when providing this power value PD can be dissipated, for example, via a cooling device (not shown) of the hybrid vehicle 1, without causing heat to accumulate in the first drive 3.

[0077] At a first time T1, the provided power P jumps from the value PD of the continuous power to a value P MAX, for example, because the user of the hybrid vehicle 1 requests increased drive power. The value P MAX corresponds to the peak power of the first drive 3. Referring to Fig. 2 At time T1, the previously explained pre-criterion 19 is therefore fulfilled and the amount of energy E provided is determined by means of numerical integration 18 (cf. step S3 in Fig. 2 and lower diagram in Fig. 3 ).

[0078] Further referring to Fig. 2 From the maximum time period T MAX and a predetermined scaling factor X, for example, a partial quantity Ex of a maximum energy quantity E MAX can be determined (see step S3 in Fig. 2 ). In the upper diagram, the value of the subset Ex corresponds to the area below the curve of the provided power P between times T1 and T2. This is indicated by hatching. The subset Ex is then used as the threshold energy quantity ES in start criterion 20 (see step S3 in Fig. 2 and lower diagram in Fig. 3 ).

[0079] The lower diagram shows a corresponding progression of the values ​​of the start parameter 10. In this case, due to the constant power value P MAX in the upper diagram, a linear progression of the start parameter 10 or the provided energy quantity E results. However, it is also conceivable that a non-linear progression results, e.g. if the provided power P has a non-constant progression.

[0080] Fig. 4 shows a schematic representation of a further embodiment of a hybrid vehicle 1 according to the invention. Fig. 4 In contrast to the hybrid vehicle 1 shown in Fig. 1 In the embodiment shown, the system has a further drive 4, which comprises an internal combustion engine 4-1, an exhaust gas aftertreatment system 4-2, and a heating element 4-3. The heating element 4-3 is switched on as a result of the signal S generated in step S4. This corresponds to starting the further drive 4 and serves to preheat the exhaust gas aftertreatment system 4-2. The internal combustion engine 4-1 can be started when the exhaust gas aftertreatment system 4-2 is preheated to a corresponding temperature.

[0081] Fig. 5 shows a flowchart of a further embodiment of a method according to the invention for controlling a drive train 2 in a hybrid vehicle 1. The Fig. 4 The method shown in Fig. 2 illustrated embodiment has a modified step S3.

[0082] In the Fig. 5 In step S3 shown, the time interval used to determine the threshold energy quantity 21 is determined differently. The time interval used for the numerical integration 18 is determined in the illustrated embodiment as the difference between the maximum time period T MAX and a preheating time period TH , which is used for preheating the Fig. 4 The value TH of the preheating period can be predetermined or, for example, determined as a function of the actual temperature of the exhaust gas aftertreatment system 4-2. Numerical integration 18 thus determines a subset Ex of a maximum energy quantity E MAX.

[0083] In a further numerical operation 17, the value of the subset Ex is assigned to the value of the threshold energy quantity ES. This value of the threshold energy quantity ES now forms the limit value for the current value of the start parameter 10 in the respective iteration of the procedure (see Fig. 6 ).

[0084] Fig. 6 shows another pair of diagrams for determining a start parameter 10 according to the further embodiment of the method according to the invention. In contrast to the Fig. 3 The first pair of diagrams shown refers to Fig. 6 shown pair of diagrams to the in Fig. 4 illustrated embodiment of the method according to the invention (cf. Fig. 4 ).

[0085] In Fig. 6 It becomes clear that the subset Ex of the maximum energy amount E MAX - in contrast to the Fig. 2 and 3 explained embodiment - can also be determined using the difference between the maximum time period T MAX and a value TH of the preheating time period (see step S3 in Fig. 4 ). Bezugszeichenliste

[0086] 1Hybrid vehicle 2Drivetrain 3First drive 4Further drive 4-1Internal combustion engine 4-2Exhaust gas aftertreatment 4-3Heating element 10Start parameters 13Gearbox 14Clutch 15Battery 17Numerical operation 18Numerical integration 19Pre-criterion 20Start criterion 30Device for controlling the drivetrain ESupplied energy quantity E MAX Maximum energy quantity ES Threshold energy quantity EX Value of a subset of a maximum energy quantity ICurrent intensity PPower provided P MAX Value of a predetermined peak power of the first drive PD Value of a predetermined continuous power of the first drive NKriterion not met SSignal to start the further drive S1First step S2Further step S3Further step S4Further step USolation TMaximum duration T0Time at start of journey T1First time T2Actual time T3End time of Maximum time T MAX Maximum time TH Preheating time XScaling factor YCriterion met

Claims

1. Method for controlling a drive train (2) in a hybrid vehicle (1), the drive train (2) having at least one first drive (3) and at least one further drive (4), the method comprising the following steps: - monitoring (S1) a power (P) provided for operating the first drive (3), - determining (S2) at least one start parameter (10) depending on the power (P) provided, - evaluating (S3) whether the at least one start parameter (10) fulfills a start criterion (20), - starting (S4) the further drive (4) if the at least one start parameter (10) fulfills the start criterion (20), characterized in that the at least one start parameter (10) is determined as an amount of energy (E) provided for operating the first drive (3), the start criterion (20) being fulfilled if the amount of energy (E) provided is greater than or equal to a threshold amount of energy (ES), the amount of energy (E) provided being determined as a time integral over the provided power (P) from a first time (T1) to an actual time (T2).

2. Method according to claim 1, characterized in that the start criterion (20) is determined depending on a value (PMAX) of a peak power of the first drive (3).

3. Method according to claim 1 or 2, characterized in that the start criterion (20) is determined depending on a value (TH) of a time period necessary for preheating the further drive (4).

4. Method according to claim 3, characterized in that the value (TH) of the time period necessary for preheating the further drive (4) is determined depending on an actual temperature of the further drive (4).

5. Method according to any of the preceding claims, characterized in that the threshold amount of energy (Es) is determined as a value (EX) of a subset of a maximum amount of energy (EMAX), the maximum amount of energy (EMAX) corresponding to the amount of energy necessary for providing the peak power over a maximum period of time (TMAX).

6. Method according to any of the preceding claims, characterized in that the determination of the at least one start parameter (10) only takes place when the power (P) provided is greater than or equal to a value (PD) of a predetermined continuous power of the first drive (3).

7. Method according to any of the preceding claims, characterized in that the starting of the further drive (20) only takes place when the power (P) provided for operating the first drive (3) has been reduced by a value which corresponds to a power required for starting the further drive (4).

8. Hybrid vehicle (1) comprising a drive train (2), wherein the drive train (2) has at least one first drive (3) and at least one further drive (4), wherein the hybrid vehicle (1) further comprises a device (30) for controlling the drive train (2), wherein the device (30) is designed to carry out a method according to any of claims 1 to 7.